The instant invention relates to biocidal coating compositions, particularly paints, in which hydrated lime is used as a biocidal agent and to method of making certain such compositions and paints.
Hydrated lime is well known as a disinfectant, biocidal, and biostatic agent. Its effectiveness for these purposes is based on its high alkalinity, a pH above about 11. In order to retain its biocidal activity after application to a desired surface, a hydrated lime must retain the high alkalinity necessary to kill microorganisms.
Unfortunately, hydrated lime is highly susceptible to environmental attack, primarily by carbon dioxide present in the ambient atmosphere. Carbon dioxide converts the hydrated lime to calcium carbonate, which does not have the alkalinity required to kill microorganisms. Such a consequence had mitigated against the use of hydrated lime in coating compositions, such as paints and whitewash, as effective long term disinfectants, biocides, or biostatic agents.
The prior parent patent applications first noted above, whose entire disclosures are hereby specifically incorporated by reference, disclose coating compositions which have overcome this problem and are effective coatings that resist degradation by carbon dioxide for prolonged periods of time. Such compositions, however, are not truly washable or cleanable with aqueous materials and their use is thereby limited. Also, as noted therein, it was not possible to use with such compositions the conventional latex vehicles used in forming paints which employ anionic or quaternary surfactants and emulsifiers.
Most interior building paints are based on a latex vehicle and their popularity results from their easy application, much lower odor, and, when dry, a good appearance and appearance retention and ability to be cleaned with soap and waer.
As noted in the prior parent applications, such conventional latex binders were incompatible with hydrated lime which results in coagulation and phase separation almost immediately upon blending with lime.